Oil removal system for refrigeration apparatus



ou. 2o, 1953 I AJ w. RUFF OIL REMOVAL SYSTEM FOR REFRIGERATION APPARATUSFiled Deo. 9, 1952 ATTORNEY Patented Oct. 20, 1953 UNITED STATES OILREMOVAL SYSTEM FOR REFRIGER- ATIGN APPARATUS Alonzo W. Ruff, York, Pa.,assigner to V. C. Patterson & Associates, Inc., York, Pa., a corporationof Pennsylvania 4 Claims.

This invention relates to refrigeration apparatus and more particularlyto oil removal systems in apparatus designed to provide extremely lowtemperatures for low temperature sto-rage of food products or for testrooms and the like.

rIt has been determined that refrigeration systems best adapted toextreme lo-W temperature applications are those which employ a surgedrum as a storage receptacle for liquid refrigerant supplied by acompressor, and in which the liquid refrigerant in the surge'drum iscirculated, preferably by means of a small positive displacement typepump, to conventional evaporators.

The problem of oil removal is unfortunately as much of a problem inapparatus of this type as in any conventional refrigeration system.There are numerous devices shown in the prior art for effecting aseparation of oil from the refrigerant and returning it to thecompressor. Refrigerants of the Freon group are all readily misciblewith lubricating oils and it is with apparatus using such refrigerantswith which the instant invention is concerned. My prior Patent No.2,617,265 illustrates one form of apparatus for achieving the desiredresults in apparatus of this type. The apparatus shown in that patentmakes use of the waste heat from the motor which drives the pump tooperate a small oil still which may or may not be constructed as a partof the surge drum itself. apparatus of this invention, however, wouldinclude locating both the pump and the oil still evaporator within therefrigerated space.

This invention has at its object the provision of apparatus foreffecting a separation of oil from the refrigerant and returning it tothe compressor in a simple and novel manner. In general, this inventionapplies to plural evaporator systems and makes use of one of theevaporators in the cold space to serve also as an oil still. A completeunderstanding of this invention may be had from reading the followingspecification in conjunction with the attached sheet of drawing, thesingle figure of which shows in diagrammatic form a preferred embodimentof the apparatus.

Referring now to the drawing, the surge drum il), compressor I I andcondenser I2 are connected together by closed conduits so that thecompressor may function to supply liquid refrigerant to the lowerportion of the surge drum IG and to withgilaw gaseous refrigerant fromthe upper prtion of the drum. Operation of the compressor may becontrolled in any convenient manner, as for example by a float switch inthe drum to maintain therein a predetermined level of liquidrefrigerant.

The preferred embodiment of the Y The remainder of the refrigerantcircuit includes a pump I3 and a plurality of evaporators I4, I5, IS andil. The pump I3 may conveniently be of the positive displacementhermetic liquid type. Closed conduits connect the inlet of the pump withthe lower portion of the surge drum, and the outlet of the pump with theinlet of each of the evaporators. It will be understood that any numberof evaporators could be used and the four shown in the drawing are forillustrative purposes only. Also, as indicated in the drawing, theevaporators may be located at substantial distances from each other.Evaporators Ill, I5 and I5 have their outlets connected to a commonreturn conduit which connects them to the upper portion of the surgedrum It. Evaporator I'i, however, has its return conduit It connected tothe suction line of the compressor. Admission of refrigerant toevaporator Il may be controlled by a conventional thermal expansionvalve I9 and bulb it. Obviously, an equally workable arrangement wouldbe to substitute a capillary tube for valve I9. Such a tube, of course,would have to be accurately proportioned for a specific design balance.

In the operation of the system therefore, the evaporator I1 functionsboth as an evaporator to cool the refrigerated space and as an oil stillto separate oil from the refrigerant. By virtue of its separate returnconnection to the suction line of the compressor, the separated oil iscarried through the return conduit it and back to the suction inlet ofthe compressor.

In order to assure a proper working pressure for this evaporator, avalve 2l is provided in the outlet conduit from the pump I3. This valveis positioned beyond the point where the evaporator I'I inlet conduit isconnected to the outlet of the pump I3. This serves then to provide aslightly higher feed pressure in the line to evaporator Il than in thelines to the remaining evaporators and valve I9 will therefore functionin normal fashion. In other words, valve ZI produces a pressuredifference to assure feeding refrigerant through control valve I9. Also,While indicated as a valve in the drawings, 2l could take any known formof restricting means.

From the foregoing, it will be apparent to those skilled in the art thatthe apparatus herein disclosed comprises a new and useful oil returnsystem especially adapted for use in connection with a specific type ofrefrigeration system applicable generally to the extreme low temperaturefield. The novel features are set forth with particularity in theappended claims.

Iclaim:

1. A refrigeration system comprising in cornbination: a surge drum;ycompressor means; condenser means; conduit means connecting said surgedrum, compressor and condenser for furnishingliquid refrigerant to-,thelower portion of said drum and removing gaseous refrigerant fromthe upper portion of said drum; a plurality of evaporators; a pumpconnected to supply liquid refrigerant from said drum to saidevaporators; means for establishing a rpressure in'the refrigerantsupply line to one of said evaporators higher than the pressure in thesupply line to the other evaporators; Ymeans for controlling theadmission of refrigerant to said one evaporator; a `closed conduitconnecting the outlet of said one evaporator to the suction'side yoflsaid compressor; and a common return conduit con necting the outlets ofthe remainder of said evaporators with saidsurge drum; Wherby said .one

:evaporator functions also as an oil still to return oil to lthecompressor.

v2. In -a refrigerationsystem .of the type'in which a compressormaintains a body ,of liquid refrigerant in a surge drum and in which apump -is connected to feed refrigerant to a plurality of Vevaporators;`an oil return system comprising: Vmeans connecting the outlet side ofone of said evaporators to the suction side of the commeans said oneevaporator, and means providing a com- `mon return for refrigerant tothe surge drum vfrom kthe remaining evaporators.

y3. A refrigeration ysystem 'comprising in cornbination: a surge drum; acompressor; a condenser; means including closed conduits connesting saiddrum, compressor and condenser in a closed refrigerant ycircuit wherebysaid compressor will function to maintain a body of liq- `uidYrefrigerant .in the basesof-sadldizurn and Withdraw gaseous refrigerantfrom the upper portion of said drum; a plurality of evaporators;

va pump; a closed conduit connected between thev inlet of said pump andthe lower portion of said surgeI-drum; a second closed conduit connected'i between the outlet of said pump and the inlet vof ,said evaporators;Valve means positioned in said -secondwconduit beyond the inlet to oneof vsaid?,evaporators; Ya third conduit connected between the outlet ofsaid one evaporator and the suction side of said compressor; a thermalexvpansion valve -connected in the inlet line of said one evaporator;and conduit means connected between the outlets of the othereyaporatorsy and the upper portion of. the surge drum.

Y1.1... A refrigeration system as defined byclaim` 1 in which the pumpis a positive displacement 'hermetio liquid type.

ALONZO W. RUFF.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,032,230 Small'etal. Feb. 25,1936 2,154,905 Kagi Apr. 18,1939 2,223,882 Beline Dec. :3, 1940 2,570,979 Phillips Oct. 9,1951

OTHER REFERENCES Air Conditioning and Refrigeration News, Sept.

yl, 1952, p. 10.

